Cystic Fibrosis

Question 1

Definition

Answer 1

Autosomal recessive disorder
Mutation in the transmembrane conductance regulator protein encoded on chromosome 7
If pulmonary disease involved, may cause morbidity and mortality

Question 2

Pathophysiology

Answer 2

Reduced Na absorption from the lumen
Reduced Cl secretion from the epithelium
Results in dehydrated mucosal layer, thick, sticky mucus, shearing and impaired bacterial killing via neutrophils

Question 3

Aetiology

Answer 3

Genetics - mutation in the transmembrane conductance regulator protein encoded on chromosome 7

Question 4

Symptoms

Answer 4

Pancreatic insufficiency leads to failure to thrive, abnormal stool and diabetes
Recurrent bronchopulmonary infection such as pneumonia, bronchiectasis, scarring, abscess
Nail clubbing
Osteoporosis
Pneumothorax
Haemoptysis

Question 5

Investigations

Answer 5

Antenatal testing - amniocentesis and chorionic villus sampling
Neonatal testing - bloodspot
Postnatal - sweat chloride (>60mmol/l is abnormal)
CXR - tram lines (dilated airways), signet rings and consolidation (mucous plugging)

Question 6

Treatment

Answer 6

High energy diet
Enteric coated enzyme pellets
For respiratory features - mucolytics, bronchodilators, antibiotics, azythromycin

Question 7

Contraindications to lung transplant

Answer 7

Other organ failure
Drug, alcohol, nicotine dependency
Malignancy within 5 years
Active systemic infection

Question 8

Effect of CFTR

Answer 8

Decreased mucociliary clearance
Increased bacterial adherence
Decreased endocytosis of bacteria

The airways are dehydrated hence the mucous will slide along it causing damage and increasing the chances of infections, instead of being cleared out. This will increase the likelihood of bacteria and infections.

Question 9

What do the mutations depend on?

Answer 9

The amount of protein
If the protein is processed correctly to the membrane
If the protein functions correctly